Been going through the ignition on the stock 292 Y-Block. Has new plugs, wires, cap & rotor, and plugs are gapped at .035"; Pertronix Ignitor and Flamethrower coil. I use a little bit of dielectric grease on the boots. The #6 plug wire boot is arcing from the outside to one of the metal clips that secures the distributor cap. Thought it might be a bad wire, so I swapped the 5 & 6 wires and the problem remained. Installed a brand new distributor cap just for grins and that just made it worse. What causes this?
Carbon track from something? I also remember I was told certain wires could not cross each oter or would jump
Just to clarify, no mattef which wire you swap, it arcs from the #6 position on the cap to the retainer/clip?
It seems to me it has to be an issue with the cap, otherwise #s 1,3 and 5 would arc also. Do you have a spare set of wires you could try? I suppose both caps you have could have the same issue, especially if they are made by the same manufacturer. Keep posting, I like a good electrifying mystery.
Yes, exactly. The distributor cap too was pretty old, but I cleaned up all the terminals, all the crusty stuff. So I thought well maybe the cap is just worn out or carbon tracked or a crack I couldn't see. Put a brandy new cap on, and it was worse, it just has a hotter arc now. Can hear it tick and see it. The engine doesn't stumble. Some years ago I had crossfire between cap towers, it shuddered then. Some dielectric in the boots seemed to help then.
Well I ordered a set of Motorcraft tonite. They aren't that expensive. The ones on there now are "roll yer own" spiral core, that ya put on the ends. I actually discovered this using my new toy - an ignition oscilloscope. I think the arcing is new, it's been super humid lately. But the #6 trace was spiked on the screen. Doh!!!
I had a buddy, 40 years ago, who would say your coil is too strong. I got my first honking big ass yellow Accel because of that, it was "too strong".
Now, if it moves around when you swap the present #6 plug around, wouldnt that indicate a large gap on that plug? Still, the secondary ign system should contain the voltage, unless there is a bad wire/boot/cap, correct?
Are you using copper wires or carbon fiber wires? With the flame thrower coil the carbon fiber wires will fail,I found out the hard way. HRP
They could be defective, I guess. They were NOS NGK, AP5FS maybe 10 miles on them. I gapped them at .030", which is the actual spec for 1964 Y-Blocks. Most V8 around then are .035", but the gap shouldn't be on the high side in any case.
These are "roll yer own", from Summit or somebody like that. They had a spiral wire internally. Fold it over, and crimp the brass end on. 7mm or 8mm iirc. I bet the Motorcraft wires (on order now) are carbon though. Hm.
Here's an obscure corner case... maybe there is an excess of silicone on the wire jackets (I'm picturing a jacketing process in the factory that uses a silicone release agent on the extrude line). Silicone conducts very well under heat... like what a 50kv spark might generate. While you're waiting on your new wires, maybe wipe the existing ones down with a wax remover like Pre-Kleano, or acetone (which might affect any writing on the wires).
Kerosene was traditional. There's an old time Tales of the Texas Rangers radio episode, where that was part of the plot. A spray bottle in wet weather is just the ticket. Most people use WD40 now. Yeah anyway thought about stuffing a big wad of dielectric in the boots, that will work but it melts and runs into the cap eventually. Thinking the wire insulation just isn't up to the task, like somebody said. Cheap generic wire, the insulation is just as important as the conductor maybe more. Plus, maybe at highway speed or under heavy load it might start breaking down an arcing again, probably somewhere else and I wouldn't know it. Although eventually I'll get an inverter for the scope and get somebody to drive while I watched.
Well there's some truth to that, the points distributor and cap, is just that. It's smaller and the terminals are spaced closer together than modern electronic ignition caps. One thing I wondered about, I'm running a lot of initial advance, around 17° and maybe rotor phasing becomes an issue, but that's getting off into the weeds. Another thing I can try though easily enough.
Depends on who ya ask. The way I understand it, a hotter coil or electronic ignition allows for a bit wider gap. But this puts a higher strain on cap, rotor, wires, and coil. A narrower plug gap should actually reduce the tendency for crossfire or arcing. At least that's how I understand it, and one reason I went back to the stock gap for the motor. There's a school of thought that says the plug gap is set by the engine and cylinder design, going to electronic ignition doesn't change that, yadda yadda. That sorta makes sense too.
No, it was showing the grounding/arcing on the display screen the initial spark voltage appears as a vertical line, each cylinder should be about the same height. When the coil has to work overtime, as in jumping a gap like that, the voltage from the coil goes way up. It could be a dud spark plug causing that I guess. Tomorrow maybe I'll swap it around with a different plug. I think the metal strap is a weak point, and it's poor insulation. A bent distributor shaft can be picked up by a scope though. Way above my pay grade. There's a shitload of information in those squiggly lines, but I don't know what I'm looking at. I think once I get this problem straightened out the patterns and waveforms should clean up a little bit more.
No not yet, thought I'd wait till it cooled down. Removing hot plugs can strip threads (maybe?) Probably OK now but will likely be tomorrow before I get around to it.
it sounds likely to me that number 6 plug might be "blocking" an easy electricity path, possibly too big gap or something interrupting the path , so the spark current is forced to take an easier path. if 6 plug was an easy path, the spark wouldn't have to jump a tougher path to the clip. it jumps to the clip only because that path is easier than the plug path. Maybe a very hard to detect crack in the cap around #6 that became a good path? WHY BE ORDINARY ?
^^ Keep your quote above in mind while you're troubleshooting. ^^ Ignition secondary voltage (or any voltage for that matter) seeks to follow the path of least resistance. In this case that's anything between the coil tower and the plug gap. Increased air gaps between the cap and rotor contacts, resistor plug wires, poorly crimped terminals, resistor plugs, bigger plug gaps, all increase secondary resistance. And moisture, poor insulation, cracks and carbon tracking will provide an easier path for current to find its way to ground before it reaches the plug gap.
Well OK, ya talked me into it. Installed a good clean used plug in the #6 hole. Now it's still arcing at the same place, and I figured I better check the #1 side, I didn't get that far, it's arcing from both + and - terminals on the coil itself! A frickin' light show. Tick tick tick, sparks here, there, etc. It seems to idle OK, is what's weird. Humidity in the garage is probably 90+ % right now, but it shouldn't do this??
Well I thought of that, so I installed my emergency distributor cap. Brand new, US made with brass contacts. That made it worse, if anything.
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